/*

 * Licensed to the Apache Software Foundation (ASF) under one

 * or more contributor license agreements.  See the NOTICE file

 * distributed with this work for additional information

 * regarding copyright ownership.  The ASF licenses this file

 * to you under the Apache License, Version 2.0 (the

 * "License"); you may not use this file except in compliance

 * with the License.  You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

package com.bff.gaia.unified.sdk.io.gcp.bigquery;



import com.bff.gaia.unified.sdk.transforms.DoFn;

import com.bff.gaia.unified.sdk.transforms.windowing.BoundedWindow;

import com.bff.gaia.unified.sdk.values.KV;

import com.bff.gaia.unified.sdk.values.ShardedKey;

import com.bff.gaia.unified.vendor.guava.com.google.common.annotations.VisibleForTesting;



import java.io.IOException;

import java.util.UUID;



/**

 * Fn that tags each table row with a unique id and destination table. To avoid calling

 * UUID.randomUUID() for each element, which can be costly, a randomUUID is generated only once per

 * bucket of data. The actual unique id is created by concatenating this randomUUID with a

 * sequential number.

 */

@VisibleForTesting

class TagWithUniqueIds<ElementT>

    extends DoFn<KV<ShardedKey<String>, ElementT>, KV<ShardedKey<String>, TableRowInfo>> {

  private transient String randomUUID;

  private transient long sequenceNo = 0L;



  @StartBundle

  public void startBundle() {

    randomUUID = UUID.randomUUID().toString();

  }



  /** Tag the input with a unique id. */

  @ProcessElement

  public void processElement(ProcessContext context, BoundedWindow window) throws IOException {

    String uniqueId = randomUUID + sequenceNo++;

    // We output on keys 0-50 to ensure that there's enough batching for

    // BigQuery.

    context.output(

        KV.of(

            context.element().getKey(), new TableRowInfo(context.element().getValue(), uniqueId)));

  }

}